Process for the dehydrogenation of liquid and gaseous petroleum hydrocarbons



, tete PROCESS FOR THE DE lI'ROGENATION F LIQUID AND GASEOUS PETROLEUM HY- DROCARBONS h Herman B. Kipper, Accord, Mass.

No Drawing. Application January 6, 1941, Serial No. 373,322

2 Claims.

tion of a metal from the group consisting of' nickel, cobalt, manganese, antimony, and tin toether with an oxide of a metal from the said group may be used in place of copper and iron and their respective oxides and it is practically certain that other metals and their oxides may be similarly substituted.

In place of copper and iron oxide, nickel, cobalt, tin, antimony and chromic oxides have been satisfactorily substituted as also molybdic, tungstic and vanadic acids or their anhydrides, actually, of course, oxides. Mercury and arsenic have been eliminated from our study because of their idiosyncrasies respectively to liquify and to poison.

Hydroxides, as ferric hydroxide, copper hydroxide, chromic hydroxide, etc., may be satisfactorily substituted for oxides. It goes without saying that salts that would decompose under the operating conditions to oxides might be substituted for the respective oxides.

From the operational data it will be seen that the elements under consideration cannot be classified under a single group or even several groups of the atomic table. Applicant has chosen at least one element from a group for experimentation thus far completed. There is one property that is common to all the metals or elements that have been found operationally serviceable to the processing. The metals under consideration constitute the group of so-called common elements known to form lower and higher oxides. They also constitute the same group of metals or elements that applicant found serviceable in selective oxidation of petroleum hydrocarbons to unsaturated hydrocarbons when he employed nitric acid for such oxidation purposes. Description of this processing is contained in his Patent No. 2,224,603 of December'lo, 1940. In his nitric I acid oxidation processes applicant now also is using a combination of metallic oxides and metals.

Applicant has employed not only metals and oxides in the powdered or finely divided state, suitably supported, as on asbestos, but also the so-called granular and wire forms of both metals and oxides.

An example of his operation when using powdered'or finely divided constituents in his catalytic combination is the following: one hundred and fifty grams of powdered copper, fifty grams of copper oxide and thirty-five grams of ferric hydroxide Were mixed and spread on two hundred grams of asbestos fiber and cemented there-- to by an aqueous colloidal aluminum hydrate.

Employing the above catalytic combination at about three hundred degrees centigrade, practically no carbon dioxide was found in the residual gas when operating with seven percent oxygen and ninety-three percent of nitrogen. When operating at the above temperature and with twenty percent oxygen and eighty percent of nitrogen, about 0.5 percent carbon dioxide and 0.5 percent oxygen were found in the residual gas. Thus, even when using air, about a ninetyseven percent selective oxidation was established. Operations, although not as good as the above, at much lower temperatures, as low as one hundred twenty-five degrees centigrade and as high as four hundred degrees centigrade showed selective oxidation.

Generally speaking, selective oxidations or dehydrogenations when using the'optimum temperature of operation and finely divided catalysts and air, or about twenty percent of oxygen and eighty percent of nitrogen, of from ninety to ninety-nine percent efiiciency were secured. Even when operating with rather coarse granular copper and ferric oxide, or so-called scales, at about two hundred fifty degrees centigrade in the exit gases there was found about nine percent of oxygen and one percent of carbon-dioxide, so that better than fifty percent of the oxygen of the air employed had reacted with hydrogen and only five percent with carbon. At about three hundred degrees centigrade, using the same catalytic combination, about four percent of oxygen and two percent of carbon-dioxide were found in the exit gases. Thus at the latter temperature about seventy percent of the oxygen had reacted with the hydrogen and ten percent with carbon and twenty percent remained unutilized.

This dehydrogenation work was carried out in a chrome nickel iron tube, about six feet long, 1 internal diameter, heated by electric resistance furnaces. In the above noted case,

the tube was filled with five kilograms of granular copper and two hundred fifty grams of iron oxide scales. Copper oxide was not used, as under the operating conditions it duced to copper.

is gradually re- A superatmospheric pressure of from fifteen to sixty pounds was employed. A petroleum fuel oil of about 0.87 specific gravity was used. This was passed through the reaction tube at the rate of about one liter per hour and air was forced through the tube at about four liters per minute. Operating similarly as described, but with the catalyst made up of three kilograms of granular copper, one kilogram of rather coarse iron turnings and two hundred fifty grams of iron oxide scales at about two hundred fifty degrees centigrade, no carbon-dioxide was found in the residual gas but the latter showed a twelve percent oxygen content. At three hundred degrees, about three-tenths percent carbon-dioxide was found and nine percent of oxygen. At about three hundred fifty degrees,

one and two-tenths percent of carbon-dioxide and two percent of oxygen were found. Thus iron requires a higher operating temperature but the formation of carbon-dioxide is kept at a very low figure.

' It was found, unfortunately, that. the so-called iron oxide scales gradually disintegrate at the operating temperatures described, so that the latter would not be serviceable for commercial operation. In employing finely divided particles of the catalysts and a carrier, as asbestos fiber, the former have to be cemented to the carrier, as with calcium silicates, aluminum hydroxide, etc. The method is not wholly satisfactory. To get perfect cementation without vitiation of the catalysts has been found difficult. Therefore, applicant employed the granular form of catalysts differences in results were found when usin such variation in the flow of gases. The better catalytic combinations are hence highly efilcient. In commercial bubbling towers for the granular forms of catalysts and suitably rotating housings for the carrier cemented catalysts exceptional dehydrogenation efficiencies should be secured. Applicant has operated at atmospheric to two hundred fifty pounds superatmospheric pressure, but the relatively low superatmospheric pressures used, when all points are considered, are probably the most commercially suitable.

Using seventy grams of nickel powder, thirty grams of chromic oxide, the green oxide, spread on one hundred fifty grams of asbestos fiber as carrier, at two hundred fifty degrees and thirty pounds pressure, the residual gases showed no carbon-dioxide content and nine percent of oxygen; at three hundred degrees four-tenths percent of carbon-dioxide was found present in asbestos fiber as carrier at two hundred fifty degrees and about fifty pounds pressure,,no carbonnoted and was very gratified and surprised to dioxide and nine and two-tenths percent oxygen were found; and at three hundred degrees also no carbon-dioxide and one and two-tenths percent of oxygen.

With the use of seventy grams of powdered tin 'andn thirty grams of the anhydride of tungstic acid spread on one hundred eighty grams of asbestos fiber, no carbon dioxide was found and nine percent of oxygen; at three hundred degrees there was found six-tenths percent of carbon dioxide and eight-tenths percent of oxygen was left in the residual gas.

It will thus be noted that antimony proved an excellent catalyst. Silver, gold and platinum come fully within the category of metallic elements found efilcient by applicant, but because to disintegrate and after breaking up the fines are discarded and the material obtained on a twenty-mesh screen used for the catalyst.

In using the oxides of chromium, molybdenum, tungsten and vanadium in conjunction with fer rlc and other metal oxides, chromates, tungstates, etc. possibly are formed. However, these act similarly to the oxides, or as if they were in separate physical and not chemical combinations, so that such possible chemical combinations should remain inherent to the processing of applicant. The same general statement would, of course, apply to manganates and plumbates. On the other hand the barium salts of tungstic and molybdic acids were tried and found practically valueless in applicant's dehydrogenation work. It is thus only the combination of metallic oxides and metals already outlined that act with high emciency in the dehydrogenation processing described.

The rate of fiow of oil through the reaction tube may, of course, be altered at will and in accordance with the percentage of unsaturation or dehydrogenation desired. The rate of flow of air through the tube was varied at from one to five liters per minute. Usually, about four liters were used. Above five liters the tube when using the asbestos carrier was liable to plug and local heating influenced the results. No very marked of high cost he has conducted no experimentation with the latter two elements, although he used silver as a catalyst in considerable experimentation in his'nitric acid selective oxidations. The cheaper metals give nearly one hundred percent effective dehydrogenations as by the processing described. The rarer elements, such as osmium, titanium, thalium, etc. should probably also serve emciently for the dehydrogenation work described, but it would appear rather absurd to induce higher costs into operational work when the same has been established practically one hundred percent efficiently by lower cost' methods.

Finally, for his oil dehydrogenation work, about two hundred grams of ferric oxide were fused with one hundred grams of silver vanadate, one hundred grams of molybdenum trioxide and one hundred grams of antimony oxide. The mass was broken up and the fines passing through a twenty-mesh sieve discarded. The remainder of about three hundred seventy grams was mixed with two and one-half kilograms of granular copper and two and one-half kilograms of granular nickel and the reaction tube filled withthis catalytic combination. At two hundred fifty degrees centigrade and fifty pounds pressure, threetenths percent carbon-dioxide was found in the residual gases and eight and eight-tenths percent of oxygen. At three hundred degrees about one and two-tenths percent of carbon-dioxide was found present and six-tenths percent of oxygen. Air was passed through the reaction tube at the rate of about four litersper minute and oil oi 0.87 specific gravity at the rate of about one liter per hour. Judging from the use of the finer powders studied, crushed antimony lumps and ferric oxide fused with antimony oxide should act similarly to the above catalytic combination or possibly even more efiiciently.

A catalytic combination made by precipitating onto an asbestos fiber copper oxide and iron hydroxide from their sulphates used in equimolecular proportions by an aqueous sodium hydroxide was employed for selectively oxidizing a commercial butane gas. About fifty grams of ferric hydroxide and the same weight of copper oxide were deposited on one hundred and fifty grams of the asbestos fiber and, after drying,

one hundred grams of powdered copper was further added to' make up the catalytic combination.

Using the above combination and operating at about two hundred twenty-five degrees centigrade and thirty pounds superatmospheric pressure, neither carbon-dioxide nor oxygen were found in the residual gas, so that the twenty percent oxygen and eighty percent nitrogen oxidizing mixture had acted one hundred percent selectively. Air was forced through the reaction tube at about four liters per minute and the butane gas at about one and one-half liters per minute.

Applicant has found that the catalysts act the same with the hydrocarbon gases as with petroleum hydrocarbon oils, only that considerably lower temperatures must be employed with the gases. Various gravities of oils were employed from kerosene to fuel oils of 0.92 specific gravity, however, without the necessity of making practically any changes in the operations. This was true even with the mixture of about half gasoline and half kerosene.

The unsaturated ordehydrogenated petroleum oils produced have been condensed with resins to give drying oils. For these condensations, applicant has used double chlorides, as those of cadmium and sodium and potassium and copper. He has found these to act similarly to solid acid phosphates and solid hydrogen metallic phosphates. To free these oils from a red discoloration, applicant has found that aldol is very efficient.

As an example of making an oil of this sort, a dehydrogenated oil, in which about three percent unsaturation had beenproduced, from a 0.87 specific gravity petroleum oil, was distilled under vacuum. Distillation took place between eighty and two hundred ninety-five degrees centigrade. In this oil heated to about eighty to ninety degrees, there was then dissolved of from five to ten percent of a natural resin, 9. white colophony resin being generally employed, and

' about thirty grams of finely divided cadmium and potassium chloride were added. The oil was held at the above temperature for about forty-five minutes under powerful stirring and filtered of! from the catalysts. Both lower and considerably higher temperatures were also used for these condensations, but at too high a temperature darkening of the oil becomes excessive. Instead of using distillation the dehydrogenated oils were washed with a dilute aqueous solution of sulphuric or phosphericacid and finally with a small percentage of aldol. The later has proved an excellent basis for purification of these dehydrogenated oils. A light lemon-yellow drying oil was produced having excellent drying oil properties.

Chlorinated petroleum hydrocarbons may be subjected to the processing described by applicant and he has carried out extensive work of this nature. Also operating with the preferred catalysts described and with five percent oxygen and ninety-five percent of nitrogen at four hundred degrees centigrade and thirty pounds superatmospheric pressure, a ninety-nine percent selective oxidation was secured, and even at one hundred twenty-five degrees with air and butane considerable dehydrogenation took place. Finally, it may be said that the dehydrogenation steps may be carried out fairly successfully even at atmospheric pressure and it is quite probable that sub-atmospheric pressures might be used. Applicant made no study oi this latter point, as he deemed it was of no commercial advantage over other processing described.

Applicant has not given one percent of the dehydrogenation analyses carried out, but he believes that has has given a sufflcient number and representative variation of these fully to establish his basis of operation and invention. It goes without saying that temperature and pressure and catalytic combinations could be multiplied ad infinitum without digressing from the fundamentals of the invention described. As an example, for instance, he added five percent of oxygen to air in order to operate with percentages of oxygen higher than twenty, but the relative carbon-dioxide then rises rapidly and 0 he cannot see that any advantage would be gained by the latter procedure, as air is a pretty cheap commodity.

. I claim:

1. In a process for the dehydrogenation of gaseous and liquid petroleum hydrocarbons, the step of subjecting the said hydrocarbons to oxygen and an inert gas at temperatures of one hundred and twenty-five to four hundred degrees centigrade and at superatmospheric pressures in the presence of a catalyst prepared by fusion oi a mixture of at least one metal selected from the group consisting of copper, iron, nickel, cobalt, silver, tin, lead, mercury, molybdenum, tungsten, and vanadium with at least one oxide or the said group.

2. In a process for the dehydrogenation of a liquid petroleum hydrocarbon 01' from 0.8 to 0.95 specific gravity, the step or subjecting the said hydrocarbons to air at about three hundred degrees centigrade and thirty pounds superatmospheric pressure in the presence or granular metallic copper and metallic nickel and ferric oxide-fused with molybdic trioxide, antimony de and silver vanadate, and the fused mass crushed into granular particles as a catalytic combination.

HERMAN B. KIPPER. 

